livecd ~ # mac-fdisk /dev/hda
/dev/hda
Command (? for help): p
/dev/hda
        #                    type name                 length   base     ( size )  system
/dev/hda1     Apple_partition_map Apple                    63 @ 1        ( 31.5k)  Partition map
/dev/hda2         Apple_Bootstrap bootstrap              1600 @ 64       (800.0k)  NewWorld bootblock
/dev/hda3         Apple_UNIX_SVR2 swap                2097152 @ 1664     (  1.0G)  Linux swap
/dev/hda4         Apple_UNIX_SVR2 root               37980272 @ 2098816  ( 18.1G)  Linux native

Block size=512, Number of Blocks=40079088
DeviceType=0x0, DeviceId=0x0

Command (? for help): q
livecd ~ # mkfs.ext3 /dev/hda4
mke2fs 1.38 (30-Jun-2005)
Could not stat /dev/hda4 --- No such file or directory

The device apparently does not exist; did you specify it correctly?
livecd ~ # mkswap /dev/hda3
/dev/hda3: No such file or directory